Search results for " Spectra"

High-resolution study of some doubly excited vibrational states of PH2D: the m1 + m2, m2 + m5, m2 + m3, and m2 + m6 bands

2004

Abstract The absorption bands ν 1 + ν 2 , ν 2 + ν 3 , and ν 2 + ν 6 of PH 2 D have been recorded for the first time using a high-resolution Bruker 120 HR interferometer, and rotationally analyzed. Some transitions belonging to the very weak band ν 2 + ν 5 and enhanced in intensity by strong interactions with the ν 1 + ν 2 band were also assigned. Sets of parameters obtained from the fit reproduce experimental line position of the bands ν 1 + ν 2 and ν 2 + ν 3 with about the experimental accuracy. The residuals of the ro-vibrational energies of the ν 2 + ν 6 band are about 10 times larger. Reasons for the poorer reproduction of the latter data are given.

Cross-Spectrum PM Noise Measurement, Thermal Energy, and Metamaterial Filters.

2017

International audience; Virtually all commercial instruments for the measurement of the oscillator PM noise make use of the crossspectrum method (arXiv:1004.5539 [physics.ins-det], 2010). High sensitivity is achieved by correlation and averaging on two equal channels, which measure the same input, and reject the background of the instrument.We show that a systematic error is always present if the thermal energy of the input power splitter is not accounted for. Such error can result in noise underestimation up to a few decibels in the lowest-noise quartz oscillators, and in an invalid measurement in the case of cryogenic oscillators. As another alarming fact, the presence of metamaterial com…

The Intensities of Methane in the 3–5 μm Region Revisited

2001

The analysis of the linestrengths of the infrared spectrum of methane (12 and 13) in the 3-5 µm region has been revisited on the basis of new measurements from Fourier transform spectra recorded at Kitt Peak under various optical densities. A simultaneous fit of these new data with previously reported tunable difference-frequency laser data has been done. An effective transition moment model in tensorial form up to the third order of approximation within the Pentad scheme has been used. The standard deviations achieved are very close to the experimental precision: 3 and 1.5%, respectively, for the two sets of data for the (12)CH(4) molecule, representing a substantial improvement with respe…

Line Identification of Atomic and Ionic Spectra of Holmium in the Visible Spectral Range. I. Spectrum of Ho i

2019

Compressive single-pixel multispectral Stokes polarimeter

2014

We present a single-pixel system that performs polarimetric multispectral imaging with the aid of compressive sensing techniques. We experimentally obtain the full Stokes spatial distribution of a scene for different spectral channels.

Stark broadening of hydrogen spectral lines with fine structure effects

2004

Formalism and numerical code have been elaborated for calculation of hydrogen line profiles in conditions of plasma in which Stark broadening and fine energy splitting are comparable and it is not possible to neglect either of them. It corresponds to the range of electron densities $10^{11} < N_e ({\rm cm}^{-3}) < 10^{15}$ . Lamb shift and spontaneous emission effects have also been included. Computer simulation method was applied in the calculations. Final results have been compared with experimental and theoretical findings by other authors.

Diagrammatic expansion for positive spectral functions beyond GW : Application to vertex corrections in the electron gas

2014

We present a diagrammatic approach to construct self-energy approximations within many-body perturbation theory with positive spectral properties. The method cures the problem of negative spectral functions which arises from a straightforward inclusion of vertex diagrams beyond the GW approximation. Our approach consists of a two-steps procedure: we first express the approximate many-body self-energy as a product of half-diagrams and then identify the minimal number of half-diagrams to add in order to form a perfect square. The resulting self-energy is an unconventional sum of self-energy diagrams in which the internal lines of half a diagram are time-ordered Green's functions whereas those…

Screening of microalgae and LED grow light spectra for effective removal of dissolved nutrients from cold-water recirculating aquaculture system (RAS…

2019

Popularity of recirculating aquaculture systems (RAS) is increasing. Because of the high water recirculation rate, dissolved nutrients originating from fish feed are concentrated enough in RAS wastewater (WW) to enable growth of primary producers, e.g. microalgae. This study evaluated nitrate-nitrogen (NO3-N) and phosphate-phosphorus (PO4-P) removal efficiency of ten temperate zone freshwater microalgae species during their exponential growth phase in unfiltered RAS WW at 17 ± 0.5 °C. Growth and nutrient uptake efficiency of six green and four non-green microalgae strains were compared between WW and reference growth medium in batch monocultures. The effect of three different LED grow light…

FT-IR investigation of the acetamide state in AOT reversed micelles

2003

The state of acetamide nanoparticles encapsulated in the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reversed micelles and dispersed in CCl4 has been investigated by Fourier transform infrared spectroscopy. The analysis of the vibrational spectra reveals even at the higher acetamide to AOT molar ratio some changes of the typical H-bonded structure of solid acetamide ascribable to their small size, confinement effects, and acetamide-AOT head group interactions. The stretching modes of acetamide CO and AOT sulfonate groups indicate unambiguously specific acetamide-AOT head group interactions.

Computational and experimental investigation of intermolecular states and forces in the benzene-helium van der Waals complex

2003

A study of the intermolecular potential-energy surface (IPS) and the intermolecular states of the perprotonated and perdeuterated benzene–He complex is reported. From a fit to ab initio data computed within the coupled cluster singles and doubles including connected triples model for 280 interaction geometries, an analytic IPS including two- to four-body atom–atom terms is obtained. This IPS, and two other Lennard-Jones atom–atom surfaces from the literature, are each employed in dynamically exact (within the rigid-monomer approximation) calculations of J = 0 intermolecular states of the isotopomers. Rotational constants and Raman-scattering coefficients for intermolecular vibrational trans…